1. Field
Exemplary embodiments of the present invention relate to a signal amplification circuit.
2. Description of the Related Art
In order to store data in the semiconductor memory device, an input buffer circuit for receiving data from another device is used. The input buffer circuit receives data from an external electronic element or electronic device, amplifies the received data, and converts the amplified data into a level which may be processed by the semiconductor memory device for example, a CMOS level.
Examples of circuits used as the input buffer circuit of the semiconductor memory device may include a differential amplifier circuit using a current mirror. Here, the differential amplifier circuit refers to an amplifier which may obtain an output proportional to a level difference between two input signals. Since the differential amplifier circuit may quickly operate by sensing a minute voltage difference, that is, a differential input signal. Therefore, during a high-frequency operation, the differential amplifier circuit may provide an output signal responding at high speed. Such a differential input signal is a voltage difference between inverted signals or a voltage difference between a reference voltage and an input signal.
Meanwhile, one of main features of the recent semiconductor memory devices is a high-speed operation. When data are transmitted from other electronic elements or electronic devices through a channel, a transmission characteristic based on a frequency of the channel has the property of a low pass filter (LPF), even though there is a slight difference depending on the length of the channel. Therefore, during the high-frequency operation, data are inevitably attenuated to some extent. Accordingly, since the voltage difference between the reference voltage and the input signal decreases due to the above-described attenuation during the high-frequency operation, the quality of the output signal of the input buffer circuit may deteriorate. For example, a slew rate of the signal may decrease at an edge where the logic value of the signal transits.
In order to resolve above concerns, some of the recent semiconductor memory devices include an equalization circuit. The equalization circuit refers to a circuit having a function of preventing the quality reduction of the output signal of the input buffer circuit, caused by the signal attenuation, and may be implemented in various manners. However since the equalization circuit includes a plurality of logic gates and the like, the current consumption of the semiconductor memory device additionally increases, and the size of the semiconductor memory device significantly increases.